Adaptive sampling interval cause-selecting control charts

This article considers the statistical adaptive process control for two dependent process steps. We construct an adaptive sampling interval Z _X control chart to monitor the quality variable produced by the first process step, and use the adaptive sampling interval Z _e control chart to monitor the specific quality variable produced by the second process step. By using the proposed adaptive sampling interval control charts, we can quickly detect and distinguish which process step is out of control. The performance of the proposed adaptive sampling interval control charts is measured by the adjusted average time to signal (AATS), which was derived by a Markov chain approach, for an out-of-control process. An empirical automobile braking system example shows the application and the performance of the proposed adaptive sampling control charts in detecting shifts in process means. Some numerical results obtained demonstrated that the performance of the proposed adaptive sampling cause-selecting control charts outperforms the fixed sampling interval cause-selecting control charts.     

食品中的泡沫

食品中的泡沫是气体分散在液体或半固体中的分散体系。在稳定的泡沫中,气泡是由有弹性的液体股或半固体膜分隔开来。气泡的直径大约从lμm到数厘米,作为分散相的气泡常常呈多面体而不是球形。由于气泡的大小以及膜厚度的不同,泡沫可能像连续相(液体)那么重,也不可能像分散相(气体)那么轻。典型     

蛋白核小球藻-解脂酵母共生体系油脂合成机制的研究

目的 为了提高小球藻在食品中的利用,开发更多有价值的副产物。方法本文主要以蛋白核小球藻-解脂酵母共生体系和小球藻单独培养体系为研究对象,采用转录组学分析手段,对共生体系培养3天和培养5天后合成代谢通路的相关差异基因进行分析,探究酵母对小球藻细胞内油脂积累的合成机制的影响。结果培养3天后,有9899个 unigenes 的表达发生显著变化,其中显著上调的有 7310 个,显著下调的有 2575 个;培养5天后,有3976个 unigenes 的表达发生显著变化,其中显著上调的有 2827 个,显著下调的有 1149 个。其中,参与脂肪酸合成代谢途径的差异基因有50个显著上调,8个显著下调;参与不饱和脂肪酸合成途径的差异基因有26个显著上调,13个显著下调。结论酵母能够通过刺激小球藻细胞内油脂代谢通路的相关基因表达,从而有利于油脂的积累     

Variable control scheme in the cascade processes

The article considers the variables process control scheme for cascade processes. We construct variable sample sizes and sampling intervals (VSSI) control charts to effectively monitor the input variable and the output variable produced by a cascade process. The performance of the proposed VSSI control charts is measured by the adjusted average time to signal derived by a Markov chain approach. An example of the metallic film thickness of the computer connectors system shows the application and the performance of the proposed VSSI control charts in detecting shifts in means of the cascade process. Furthermore, the performance of the proposed VSSI control charts and the fixed sample sizes and sampling intervals control charts are compared by numerical analysis results. These demonstrate that the former is much faster in detecting small and medium shifts. The optimum VSSI control charts are also proposed using optimization technique when quality engineers cannot specify the values of the variable sample sizes and sampling intervals. It has been found that the optimum VSSI control charts work and are thus suggested whenever quality engineers cannot specify the values of variable sample sizes and sampling intervals. Furthermore, the impacts of misusing Shewhart charts to monitoring the process means on the cascade process are also investigated.     

Relating vegetation dynamics to temperature and precipitation at monthly and annual timescales in Taiwan using MODIS vegetation indices

To predict the responses of the timing, duration, and density of photosynthetically active plant cover to a changing climate, it is necessary to first quantitatively describe the relationships between temporal and spatial patterns of vegetation cover and both spatial and inter-annual variation in temperature and precipitation. We examined these relationships at multiple scales in Taiwan using monthly maximum composite values of MODIS-NDVI and MODIS-EVI between 2000 and 2012. The two vegetation indices were highly correlated to each other on a monthly basis for non-forest land-cover types, but correlated poorly in forests, probably due to the saturation of NDVI. However, the two indices were equally sensitive in detecting the onset and offset of growing season for all vegetation types. We found that EVI was positively related to both precipitation and temperature on a monthly timescale, although the relationships were not significant at the annual timescale. The much greater variation in monthly than in annual precipitation and temperature probably explains this difference. At low elevations, precipitation had a positive effect and temperature had a negative effect on EVI; however, at high elevations, which are mostly forested, both were positively related to EVI (although precipitation effects were not significant). We interpret this as evidence of water limitation of photosynthetic cover in the warmer, low-elevation parts of the island, whereas in the higher-elevation areas precipitation was usually adequate to satisfy evapotranspirative demand. This study illustrates the importance of examining the effects of precipitation and temperature on plant growth at a range of spatial and temporal scales. Specifically, finer spatial and temporal scales of analysis may better reveal climatic controls over vegetation growth than broader scales of analysis.     

Effects of imprecise measurement on the two dependent processes control for the autocorrelated observations

The observations from the process output are always assumed to be independent when using a control chart to monitor a process. However, for many processes the observations are autocorrelated and including the measurement error due to the measurement instrument. This autocorrelation and measurement error can have a significant effect on the performance of the process control. This paper considers the problem of monitoring the mean of a quality characteristic X on the first process, and the mean of a quality characteristic Y on the second process, in which the observations X can be modeled as an ARMA model and observations Y can be modeled as an transfer function of X since the state of the second process is dependent on the state of the first process. To distinguish and maintain the state of the two dependent processes with measurement errors, the Shewhart control chart of residuals and the cause-selecting control chart, based on residuals, are proposed. The performance of the proposed control charts is evaluated by the rate of true or false alarms. By numerical analysis, it shows that the performance of the proposed control charts is significantly influenced by the variation of measurement errors. The application of the proposed control charts is illustrated by a numerical example .     

Auxiliary information-based maximum generally weighted moving average chart for simultaneously monitoring process mean and variability

An auxiliary information-based (AIB) maximum exponentially weighted moving average (MaxEWMA) chart has been proposed to simultaneously monitor both increases and decreases in the process mean and/or variability, called the AIB-MaxEWMA chart, which is superior to the existing MaxEWMA chart. In this paper, we propose the AIB maximum generally weighted moving average chart, called the AIB-MaxGWMA chart, to further enhance the sensitivity of the AIB-MaxEWMA chart. Numerical simulation studies indicate that the AIB-MaxGWMA chart is sensitive to small shifts in the process mean and/or variability. The performance of the AIB-MaxGWMA chart based on average run lengths (ARLs) also outperforms than its counterparts including AIB-MaxEWMA, MaxGWMA and MaxEWMA charts. An example is used to illustrate the efficiency of the proposed AIB-MaxGWMA chart in detecting small process shifts.     

蜀南地区储层分段改造技术新进展及应用

２００９年以来,随着蜀南地区页岩气和致密气的开发,储层分段改造技术取得长足的进展。长宁、威远 页岩气分段压裂改造技术从最初的速钻桥塞＋喷砂射孔分段压裂技术发展到后来的免钻磨大通径桥塞分段压裂 技术,缩短了施工周期,还实现了关键装备（速钻桥塞）的国产化。在安岳气田和老区块部署的水平井,引入的裸眼 封隔器分段改造技术,从最初的加压座封封隔器发展到遇油膨胀封隔器,再到后期的可捞球座、可开关滑套裸眼封 隔器,解决了后期生产过程中修井和生产测井的问题。针对安岳大斜度井储层改造,试验了ＴＡＰ阀分段压裂技术、 复合桥塞分层＋“ＨｉＷＡＹ”压裂技术,取得成功,为今后蜀南地区页岩气和致密气藏的开发提供了技术储备。可回 收压裂液技术,实现了压裂液的循环利用,达到了节能减排的目的,是未来压裂液技术的发展方向。